Determining structural boundaries using blocky magnetotelluric data inversion

The magnetotelluric method has large depths of investigation and can provide important structural information in many exploration problems. The one-dimensional magnetotelluric inversion also has been applied to extract boundary information and provide the constraints for the interpretation of complementary datasets. Traditional smooth inversion based on the L(2 )norm only provides a single smooth model that it is difficult to detect the location of the geological boundary. Trans-dimensional inversion provides an effective means to determine the boundaries with uncertainty quantification but incurs significant computational costs. We present an efficient method to detect distinct interfaces from one-dimensional blocky magnetotelluric inversions using an Ekblom norm. The method leverages the Ekblom norm to assess the change in the recovered resistivity model with the threshold parameter as a means to delineate the significant boundaries in the subsurface. The threshold parameter specific to the Ekblom-norm inversion is then used to probe the variability of the inversion to obtain a more robust interface detection. Once the interfaces are detected, we calculate the average resistivity value between detected interfaces to form a final conductivity model. As a demonstration, we apply this method to a synthetic example and the field data from East Tennant in Australia. The results show that the method is effective in obtaining boundaries.